Property taxes and assessments under Mello-Roos are liens against the property and will survive a change of ownership unless paid. In ordinary real-estate purchase-and-sale transactions, liens are paid in escrow, including mortgages, taxes, judgments, and so forth. In a short sale, things are a little less predictible in most areas of the deal's negotiation, terms and documentation.
First, you are supposed to be able to rely upon your agent and broker. You are paying them a commission to represent you and to use their skills and knowledge to protect you from avoidable problems, They are fiduciaries, and can be sued if they fail to look out for you. I would ask for a written promise that the house will be free from liens.
Next, I would want the deal to be closed through an escrow with a licensed and reputable escrow holder which will prepare or at least examine all the documents, and I would want title insurance. Is there an escrow? Have you received a preliminary title report? Will you be getting title insurance? If so, what exceptions will it show?
If you are going through escrow, you can also ask the title officer or closing officer assigned to your deal to explain whether the taxes and assessments will be paid at closing, and by whom, and where that shows in the closing estimate and other papers.
As a standard practice, a buyer is entitled to receive title free from liens, or at least free form undisclosed liens and liens the buyer has not agreed to assume. However, short sales vary from deal to deal, and it is possible someone has designed a deal in which these liens are passed along with the property.
If neither your agent and broker, nor the escrow officers, can give you comfort, maybe show the deal package to a local real-estate lawyer. A quick review should not cost more than a couple hundred bucks.
